1,371 research outputs found
Soft-core baryon-baryon potentials for the complete baryon octet
SU(3) symmetry relations on the recently constructed hyperon-nucleon
potentials are used to develop potential models for all possible baryon-baryon
interaction channels. The main focus is on the interaction channels with total
strangeness S=-2, -3, and -4, for which no experimental data exist yet. The
potential models for these channels are based on SU(3) extensions of potential
models for the S=0 and S=-1 sectors, which are fitted to experimental data.
Although the SU(3) symmetry is not taken to be exact, the S=0 and S=-1 sectors
still provide the necessary constraints to fix all free parameters. The
potentials for the S=-2, -3, and -4 sectors, therefore, do not contain any
additional free parameters, which makes them the first models of this kind.
Various properties of the potentials are illustrated by giving results for
scattering lengths, bound states, and total cross sections.Comment: 22 pages RevTex, 6 postscript figure
Light hypernuclei in four-body cluster models
Detailed structure calculations in Be, H,
Li, H and Li are performed
within the framework of the microscopic two-, three- and four-body cluster
models using the Gaussian Expansion Method.Comment: 14 pages, 19 figures. To be published in Phys. Rev.
Partial Wave Analyses of the pp data alone and of the np data alone
We present results of the Nijmegen partial-wave analyses of all NN scattering
data below Tlab = 500 MeV. We have been able to extract for the first time the
important np phase shifts for both I = 0 and I = 1 from the np scattering data
alone. This allows us to study the charge independence breaking between the pp
and np I = 1 phases. In our analyses we obtain for the pp data chi^2_{min}/Ndf
= 1.13 and for the np data chi^2_{min}/Ndf = 1.12.Comment: Report THEF-NYM 94.04, 4 pages LaTeX, one PostScript figure appended.
Contribution to the 14th Few-Body Conference, May 26 - 31, Williamsburg, V
Soft two-meson-exchange nucleon-nucleon potentials. I. Planar and crossed-box diagrams
Pion-meson-exchange nucleon-nucleon potentials are derived for two nucleons
in the intermediate states. The mesons we include are (i) pseudoscalar mesons:
; (ii) vector mesons: ; (iii) scalar
mesons: ; and (iv) the
contribution from the Pomeron. Strong dynamical pair suppression is assumed,
and at the nucleon-nucleon-meson vertices Gaussian form factors are
incorporated into the relativistic two-body framework using a dispersion
representation for the pion- and meson-exchange amplitudes. The Fourier
transformations are performed using factorization techniques for the energy
denominators. The potentials are first calculated in the adiabatic
approximation to all planar and crossed three-dimensional momentum-space
-meson diagrams. Next, we calculate the corrections.Comment: 28 pages RevTeX, 8 postscript figures; revised version as to appear
in Phys. Rev.
A regional follow-up study at two years of age in extremely preterm and very preterm infants.
This thesis describes the results of the Leiden Follow-Up Project on Prematurity (LFUPP): a prospective study in three health regions in the Netherlands, which included all live born infants with gestational age (GA) LEI Universiteit Leiden(Klinisch) epidemiologisch onderzoek bij kindere
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